Expression of a monoclonal antibody (3G5) defined ganglioside antigen in the renal cortex

Expression of a monoclonal antibody (3G5) defined ganglioside antigen in the renal cortex. The monoclonal antibody (mAb) 3G5 was found, by indirect immunofluorescence, to bind to renal cortical structures in frozen sections of human, rat and calf kidneys. Double indirect immunofluorescence studies on frozen sections of rat kidneys showed that 3G5 stained only the glomerulus and the distribution of the 3G5 antigen on the glomerulus was more extensive than the staining observed with antibodies to Factor VIII antigen. 3G5 stained the proximal convoluted tubules and collecting tubules in bovine renal sections but glomeruli did not stain with 3G5. The 3G5 mAb did not stain tissue cultured bovine glomerular endothelial cells or mesangial cells, but did stain bovine glomerular epithelial cell cultures. 3G5 did not stain MDCK cell cultures. The binding of mAb 3G5 to glomeruli was investigated by immunoelectron microscopy of rat renal tissue. In contrast to the podocyte specificity on bovine glomerular cells in vitro, it was found that the specificity of 3G5 expression on rat glomerular cells in vivo was broader. No binding of mAb 3G5 was found outside the glomerulus in the rat renal cortex. Podocytes, endothelial cells and capsular epithelial cells expressed the 3G5 antigen most strongly. A lesser amount of binding was found in the glomerular basement membrane. The mesangium showed a little binding of mAb 3G5 and no binding at all was found to other cortical structures. The 3G5 antigen in rat renal tissue was found to be a glycolipid that migrated between the ganglioside markers GM2 and GM1 by immunostaining of thin layer chromatograms. The 3G5 mAb has previously been shown to react with microvascular pericytes, resting T-lymphocytes and cells of the brain, thyroid gland and adrenal gland as well as various malignancies. The significance of the tissue specific patterns of expression remains unclear and will be understood only when the function of this ganglioside is elucidated